JP2008-298058A discloses a controller of an engine which has a function of warming engine cooling water by energizing a block heater, which is installed on the engine, during an engine off period in cold climates, wherein a relationship between the presence or absence of energization of the block heater during the engine off period and a behavior of a temperature of a cooling medium immediately after the engine starts is utilized to determine whether there has been energization of the block heater during the engine off period. If it is determined that there has been energization of the block heater, an abnormality diagnosing process related to a cooling system is prevented or an abnormality diagnosing condition is changed.
However, in the case of a vehicle which includes an electric water pump for circulating engine cooling water, driving the electric water pump before the warming-up of the engine is not useful, except for a special situation, in terms of energy saving. On the other hand, if the electric water pump is not driven before the warming-up of the engine, the presence or absence of energization of the block heater cannot be determined with high accuracy, which leads to a problem that an abnormality detection of a cooling water temperature sensor, etc cannot be performed with high accuracy.